This invention relates to apparatus and methods for reading optically encoded indicia such as bar codes. More particularly, this invention relates to optical systems that project laser light toward an optically encoded target, collect light reflected from the target, and use the reflected light to generate a readable electrical signal corresponding to the encoded target.
Conventionally, scanner or bar code reader optical systems require numerous optical components to control, project, and collect light. FIG. 1 illustrates some key components of a conventional laser light focusing device 1 that are commonly found in the prior art. Lens 2 and aperture 3 are used together to focus light from laser source 4. Star washer 5 is used to hold lens 2 in place against the inner lip 6 of aperture 3.
These individual parts must be produced and assembled within narrow manufacturing tolerances for a bar code reader to function properly. Additional components such as a laser source support and a collector for incoming light (not shown) further increase the difficulty and expense of producing a bar code reader. The large number of components combined with the need for assembly and inherent tolerance limits lead to large production costs and time requirements. Furthermore, the multi-component design leads to manufacturing flaws, decreased device longevity, sensitivity to thermal and mechanical loading, and inconsistent performance. Moreover, the multi-component design is ill-adapted for miniaturization.
Therefore, it would be desirable to provide apparatus and methods for reading indicia that require a reduced number of components, reduce the cost of manufacture and assembly, reduce manufacture and assembly time, increase reliability, decrease sensitivity to thermal and mechanical loading, and increase the consistency of performance.
It would also be desirable to provide apparatus and methods for reading indicia that reduce the overall tolerance budget of the reader and therefore facilitate mass production of optical apparatus and readers.
Moreover, it would be desirable to provide a compact indicia reader with the aforementioned advantages in the form of a pen.
It is an object of the invention to provide apparatus and methods for reading indicia that require a reduced number of components, reduce the cost of manufacture and assembly, reduce manufacture and assembly time, increase reliability, decrease sensitivity to thermal and mechanical loading, and increase the consistency of performance.
It is a further object of this invention to provide apparatus and methods for reading indicia that reduce the overall tolerance budget of the reader and therefore facilitate mass production of optical apparatus and readers.
It is a still further object of this invention to provide a compact reader with the aforementioned advantages in the form of a pen.
In accordance with the present invention, a unitary body is provided for controlling the profile of light and preferably laser light in an optical system that reads optically encoded indicia. The unitary body is preferably composed of optical material and includes an aperture forming area and a beam phase modifying area to form a beam for reading an optical code. In a preferred embodiment of the invention, an inner surface of the unitary body has an aperture forming outer region and a phase forming inner region. The unitary body also has an outer surface. In a preferred embodiment, the inner region of the inner surface and the inner region of the outer surface form a wavefront forming zone and everything outside the wavefront forming zone is an aperture forming zone. The embodiments of the unitary body produce a focus free system using a micro-aperture. In a particularly preferred embodiment, the outer surface of the unitary body is a beam splitter.
In one embodiment, the inner region of the inner surface is a converging region for focusing a portion of the light to form a beam and the outer region of the inner surface is a diverging region for diverging a portion of the light away from the beam.
In a preferred embodiment, the converging region is situated concentrically within the diverging region. The converging and diverging regions act together to form a beam that is directed through a surface in an output region of the unitary body to illuminate indicia. The outer surface of the unitary body which acts as a beam splitter, may further function as a collection surface that collects incoming reflected light. By splitting the beam, collection surface redirects a portion of the incoming light to a photodetector which generates an electrical signal indicative of light intensity for use in decoding an indicia such as a bar code.
In a particularly preferred embodiment, the unitary body includes a cavity adapted to accept and provide support for a laser source. The laser source is positioned optimally for providing light and for selective formation of a beam by the aforementioned converging and diverging regions. The unitary body may further include notches or studs for supporting circuit boards or associated components to provide support to the optical and mechanical components of the indicia reader.
In another particularly preferred embodiment of the invention, a unitary body is situated within a pen-shaped housing. This embodiment of the invention has the economical and mechanical benefits above and is an example of a hand held indicia scanner in accordance with the principles of the invention that is convenient to carry and use.